Clinical features and assisted ventilation (AV) aspects of 10 neonates with early onset group B streptococcus (GBS) septicemia were compared with those of 12 randomly selected newborns with severe respiratory distress syndrome (RDS). Initial chest radiograph in the GBS group was interpreted as RDS in seven of 10 cases. Although 9 of the 10 neonates with early onset GBS were preterm, they were of a significantly higher mean birth weight (p< 0.01) and the mean gestational age (p< 0.005). The duration of rupture of fetal membranes was not significantly different between the two groups.Contrary to neonates with severe RDS, who gradually developed hypoxia necessitating AV, the neonates with early onset GBS required AV because of persistent apnea, shock, and respiratory insufficiency. During the first 24 h of life, neonates with early onset GBS were more acidotic, had significantly higher PaCO2and lower PaO2values, and required significantly higher peak inspiratory pressure (PIP) on the respirator (p< 0.01) while on AV, although the oxygen requirement was similar.